DOL_Bio_Plant Responses

1. Plant hormones serve as chemical messengers between cells and tissues. Auxin is a plant hormone that causes the cells on the shady side of the plant shoot to elongate. The response enabled by auxin is known as _____.

• 1. geotropism

• 1. transpiration

• 1. phototropism

• 1. photosynthesis

Positive thigmotropism is a response in plants in which they move and grow toward an object the plant comes into physical contact with, usually curling around the object.

This response of the shoot system benefits the plant by allowing the plant to _____________

• 1. produce more pollen for pollinators.

  2. take in more carbon dioxide to convert into glucose.

• 1. take in more carbon dioxide to convert into glucose.

• 1. absorb more water to transport to leaves.

• 1. reach more sunlight for photosynthesis.

 Students set up a controlled experiment by growing the same type of seedlings in two different locations. 

     After a period of time, the students observed the seedlings and recorded their observations in the table 

     shown.

     What caused the shoots of the seedlings on the windowsill to bend toward the window?

• 1. Hormones produced in responses to a light stimulus.

• 1. Sugars produced in response to a gravity stimulus.

• 1. Carbon dioxide produced in response to a water stimulus.

• 1. Water produced in response to a nitrogen stimulus.

   A student conducted an investigation to study phototropism in grasses.

The control group was provided full light , while the experimental group was shaded on one side. The diagrams show the average  heights and positions of the blades of the grass in the investigation.

 Which statements best explain why the grass tips of the experimental group bent toward the light? Select TWO that apply.

• 1. Water evaporates faster on the side of the plant having full light.

• 1. Light sensors in the grass tips stimulated a hormone in the shoot system.

• 1. The xylem in the root system absorbs more nutrients from the shaded side.

• 1. The side facing the light has a greater chance of absorbing carbon dioxide from the atmosphere.

• The hormone auxin accumulated on the grass tips causing the cells to grow faster on that side.

 Describe the three examples of response that occur in plants which enable plants to maintain homeostasis.